Feature request: Unmarshal Response and Marshal Request

[seantcanavan]

It's awesome being able to marshal a response and unmarshal a request but it would also be great to unmarshal a response and marshal a request as well. This would allow testing the full life cycle as well as testing lambda functions that talk to other lambda functions.

Here's an example workflow:

• Generate object to send as request
• Marshal object into api gateway request object
• Receive api gateway request
• Unmarshal request into object and process object
• Generate application response
• Marshal application response into api gateway response object
• Receive api gateway response
• Unmarshal api gateway response to object
• Read object and test for correct return values